//握手问题
#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long count = 0;
	int a[50] = {0};
	//给7个人打上标记
	for(int i = 3; i < 10; i++)
	{
		a[i] = 1;
	}
	//遍历
	for(int i = 0; i < 50; i++)
	{
		for(int j = 1 + i; j < 50; j++)
		{
			if(a[i] == 1 && a[j] == 1);
			else
				count++;
		}
	}
	cout << count;
	return 0;
}
